Fail fast on language keywords in method names

[andreaTP]

References #239

Tested with scripted tests since I haven't found a more suitable place.
This can be a first proposal that provides the user a better error message (it's going to fail the build anyhow).
We can, later on, decide to backtick those keywords in Scala.

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[raboof]

OK TO TEST

[raboof]

I agree, nice improvement already!

[raboof]

We can, later on, decide to backtick those keywords in Scala

Oh, cool, this is already in progress in #1236

[andreaTP]

Minor issue:
Travis keeps failing because my fork master branch is pretty old and sbt get a previousStableVersion that doesn't exists.
Ref.
https://github.com/akka/akka-grpc/blob/master/build.sbt#L54

Fixed by syncing my fork master branch with origin/master.

[andreaTP]

Is Jenkins stuck?

[raboof]

OK TO TEST

[sebastian-alfers]

All scala related fail-fast logic should be removed right?

[andreaTP]

yes!

[andreaTP]

I'll rebase after #1236 get merged.

[andreaTP]

rebased on latest master.

[raboof]

Thanks for the rebase!